Megan McArdle is a serial clear thinker... Which means, of course, that you should pay attention to her musings. From a recent post:

Most of the people who "believe" in evolution don't have much more
scientific foundation for their beliefs than a young-earth creationist
does for theirs. I would be slightly surprised to learn that the
reporters asking the questions -- or, for that matter, President Obama
-- could deliver more than a few vague sentences about how evolution
works, desperately dredged up from the Life Sciences module of their
seventh-grade science class. And many such "believers" will conveniently
discard their support for evolutionary models if their own closely held
moral beliefs are threatened -- witness the outrage when Larry Summers
suggested that biology might have produced different distributions of
mathematical ability between men and women. We're talking about a
process that determined that male black widow spiders should be eaten
after they mate. Of course it could have.

Jerry Taylor of the Cato Institute tells a story about Julian Simon, the late and great economist.He was at some environmental forum, and he said, “How many people here believe that the earth is increasingly polluted and that our natural resources are being exhausted?” Naturally, every hand shot up. He said, “Is there any evidence that could dissuade you?” Nothing. Again: “Is there any evidence I could give you — anything at all — that would lead you to reconsider these assumptions?” Not a stir. Simon then said, “Well, excuse me, I’m not dressed for church.”

I love that story, for what it says about the fixity of these beliefs, immune to evidence, reason, or anything else.

Think about how pervasive these fixed beliefs are in today's society. Think anthropogenic global warming, the welfare state, affirmative action, progressivism, conservatism, etc. How many people holding such beliefs couldn't be persuaded to change their views by any evidence whatsoever?